Invertebrate Biodiversity in Antarctic Dry Valley Soils and Sediments |
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Authors: | Amy M Treonis Diana H Wall Ross A Virginia |
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Institution: | (1) Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, Colorado 80523 , US;(2) Environmental Studies Program, Dartmouth College, Hanover, New Hampshire 03755, USA , US |
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Abstract: | We studied invertebrate communities across a transition zone between soils and stream sediments in the cold desert landscape
of Taylor Valley, Antarctica. We hypothesized that hydrological and biogeochemical linkages in the functionally important
transition zone between streams and surrounding soils should be important in structuring invertebrate communities. We compared
invertebrate communities along transects beginning in the saturated sediments under flowing stream water and extending laterally
through the hyporheic zone to the dry soils that characterize most of the dry valley landscape. Nematodes, rotifers, and tardigrades
assembled into different communities in soils and sediments, but there was no relationship between the total abundance of
invertebrates and moisture. Community diversity was, however, influenced by the moisture and salinity gradients created with
distance from flowing waters. The wet, low-salinity sediments in the center of the stream contained the most invertebrates
and had the highest taxonomic diversity. Adjacent to the stream, communities in the hyporheic zone were influenced strongly
by salt deposition. Abundance of invertebrates was low in the hyporheic zone, but this area contained the most co-occurring
nematode species (three species). In dry soils, communities were composed almost entirely of a single species of nematode,
Scottnema lindsayae, an organism not found in the stream center. These results suggest spatially-partitioned niches for invertebrates in soils
and sediments in the dry valley landscape based on proximity to sources of moisture and the interactive effects of salinity.
Received 22 September 1998; accepted 16 April 1999. |
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Keywords: | : McMurdo Dry Valleys Antarctica soils streams hyporheic zone invertebrates nematodes rotifers tardigrades anhydrobiosis |
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